diff --git a/frontend/src/handler-utils/respond-to-matching-request.ts b/frontend/src/handler-utils/respond-to-matching-request.ts
index 22f89ceae..b28230ce9 100644
--- a/frontend/src/handler-utils/respond-to-matching-request.ts
+++ b/frontend/src/handler-utils/respond-to-matching-request.ts
@@ -62,8 +62,8 @@ export const respondToTestRequest = <T>(req: NextApiRequest, res: NextApiRespons
     res.status(405).send('Method not allowed')
   } else if (!isTestMode) {
     res.status(404).send('Route only available in test mode')
-  } else if (req.socket.remoteAddress !== '127.0.0.1' && req.socket.remoteAddress !== '::1') {
-    res.status(403).send('Request must come from localhost')
+  } else if (!['127.0.0.1', '::1', '::ffff:127.0.0.1'].includes(req.socket.remoteAddress)) {
+    res.status(403).send(`Request must come from localhost but was ${req.socket.remoteAddress}`)
   } else {
     res.status(200).json(response())
   }